pgfcache compiles PGF images to PDF only when needed (i.e., after you made changes to a figure). Otherwise, the static PDF is served, severely cutting compilation time for figure-heavy documents (think tikz-externalize for PGF images). Also, I have specifically designed it to play well with figures that were created with Matplotlib's PGF backend.

Using the package is easy. A minimal example would be:

\documentclass{article}
\usepackage{pgfcache}

\setpgfpreamble{%
  \usepackage{amsmath}
  <other packages that are needed to compile your PGF images, e.g. fonts>
}

\begin{document}
	\importpgf{path/to/pgffile}{myfigure.pgf}
\end{document}

Your file then has to be compiled with the option -shell-escape to pdflatex, e.g.:

pdflatex -synctex=1 -shell-escape -interaction=nonstopmode "yourfile".tex

You will also have to create a folder called _pgfcache in the parent folder of your TeX document. This is where all the pre-compiled figures will go.

If you specify an output directory (by adding -output-directory=<output> to the pdflatex command above), you should create the _pgfcache folder in that output directory. Additionally, you have to add \usepackage[outdir=<output-dir>]{pgfcache} to the preamble of your LaTeX document (see example).

The package has only rudimentary error checks. If you run into errors, you should first check whether your figures are compiled correctly (by looking at the logs in the _pgfcache folder). Chances are, you just need to specify additional packages with \setpgfpreamble, or delete the cache and try again. Otherwise, feel free to contact me or raise an issue.

Also note that pgfcache only works with PDFLaTeX (no XeLaTeX or LuaLaTeX support).